Independent sidebar field loading

[benjaminpkane]

Converts the /aggregations route into the new aggregation field which provides the needed aggregation dataset with respect to a path and the path's field type, e.g. a ground_truth_detections.label which is a StringField.

Also improves loading behavior by allowing filters to be expanded while counts are still loading, and delays make networks until a component is visible/expanded, i.e. a confidence slider.

TODO:

• [ ] group regressions
• [ ] refresh regressions